# knight

From spray v1.0-6
by Robin K S Hankin

##### Generating function for a chess knight and king

Generating function for a chess knight and king on an arbitrarily-dimensioned chessboard

##### Usage

```
knight(d=2)
king(d=2)
```

##### Arguments

- d
Dimensionality of the board, defaulting to 2

##### Value

Returns the generating function of the piece in question.

##### Note

The pieces are forced to move; if they have the option of not moving, add 1 to the returned spray. The vignette contains a short discussion.

##### Examples

```
# NOT RUN {
## How many ways can a knight return to its starting square in 6 moves?
constant(knight()^6)
## How many in 6 or fewer?
constant((1+knight())^6)
## Where does a randomly-moving knight end up?
d <- xyz(2)
kt <- (1+knight())*d^2/9
persp(1:25,1:25,as.array(d*kt^6))
## what is the probability that a 4D king is a knight's move from
## (0,0,0,0) after 6 moves?
sum(value(((king(4)/80)^4)[knight(4)]))
# }
```

*Documentation reproduced from package spray, version 1.0-6, License: GPL (>= 2)*

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